Well, it hasn't been a deliberate and intentional effort to exclude those without property or net worth from the decision making process - People like that, who reside at the bottom of the hierarchies they inhabit, have never in history been looked to for guidance or input on any decision. I'm making an evolutionary biology claim: Folks with no clout can only have a say if it is deliberately & intentionally given to them. It's the opposite of your speculation that it's been taken from them.
And frankly why _should_ someone who cannot gather value for themselves have a say in economic decisions that will affect others? The reason we have these big evil hierarchies, where the poor are dispossessed and a small group of tycoons at the top make the decisions, is because they have a track record of good decisions. If you suddenly took some progressive initiative to invite some idlers to give input on tax law, they might make a decision that inadvertently lowers your country's GDP by half a percent for five years.